<!--
  Copyright (C) Igor Sysoev
  Copyright (C) Nginx, Inc.
  -->

<!DOCTYPE article SYSTEM "../../../../dtd/article.dtd">

<article name="转换rewrite规则"
         link="/cn/docs/http/converting_rewrite_rules.html"
         rev="1"
         lang="cn">


<section name="重定向到主站">

<para>
共享站点的管理员，习惯于<i>只</i>在Apache下使用.htaccess文件配置<i>所有</i>信息，通常会将下面规则

<programlisting>
RewriteCond  %{HTTP_HOST}  example.org
RewriteRule  (.*)          http://www.example.org$1
</programlisting>

翻译成这样：

<programlisting>
server {
    listen       80;
    server_name  www.example.org  example.org;
    if ($http_host = example.org) {
        rewrite  (.*)  http://www.example.org$1;
    }
    ...
}
</programlisting>
</para>

<para>
这种做法是错的，复杂而且低效。正确的方式是为<literal>example.org</literal>定义一个单独的服务器：

<programlisting>
server {
    listen       80;
    server_name  example.org;
    return       301 http://www.example.org$request_uri;
}

server {
    listen       80;
    server_name  www.example.org;
    ...
}
</programlisting>

<note>
在0.9.1版本（含）以前，可以这样实现重定向：
<programlisting>
    rewrite      ^ http://www.example.org$request_uri?;
</programlisting>
</note>

</para>

</section>


<section>

<para>
再举一个例子，处理一个和刚才相反的逻辑：既不是来自<literal>example.com</literal>，又不是来自<literal>www.example.com</literal>：

<programlisting>
RewriteCond  %{HTTP_HOST}  !example.com
RewriteCond  %{HTTP_HOST}  !www.example.com
RewriteRule  (.*)          http://www.example.com$1
</programlisting>

应该按下面这样分开定义<literal>example.com</literal>、<literal>www.example.com</literal>和其他站点：

<programlisting>
server {
    listen       80;
    server_name  example.com www.example.com;
    ...
}

server {
    listen       80 default_server;
    server_name  _;
    return       301 http://example.com$request_uri;
}
</programlisting>

<note>
在0.9.1版本（含）以前，可以这样实现重定向：
<programlisting>
    rewrite      ^ http://example.com$request_uri?;
</programlisting>
</note>

</para>

</section>


<section id="converting_mongrel_rules"
        name="转化混合规则">

<para>
典型的混合规则如下：

<programlisting>
DocumentRoot /var/www/myapp.com/current/public

RewriteCond %{DOCUMENT_ROOT}/system/maintenance.html -f
RewriteCond %{SCRIPT_FILENAME} !maintenance.html
RewriteRule ^.*$ %{DOCUMENT_ROOT}/system/maintenance.html [L]

RewriteCond %{REQUEST_FILENAME} -f
RewriteRule ^(.*)$ $1 [QSA,L]

RewriteCond %{REQUEST_FILENAME}/index.html -f
RewriteRule ^(.*)$ $1/index.html [QSA,L]

RewriteCond %{REQUEST_FILENAME}.html -f
RewriteRule ^(.*)$ $1/index.html [QSA,L]

RewriteRule ^/(.*)$ balancer://mongrel_cluster%{REQUEST_URI} [P,QSA,L]
</programlisting>

转换成nginx配置应该是这样：

<programlisting>
location / {
    root       /var/www/myapp.com/current/public;

    try_files  /system/maintenance.html
               $uri  $uri/index.html $uri.html
               @mongrel;
}

location @mongrel {
    proxy_pass  http://mongrel;
}
</programlisting>
</para>

</section>

</article>